Should you rule out anything as a possibility if it hasn't been 100% debunked? Remember, there's a significant difference between probability and possibility.

Well there in lies the problem, virtually nothing cannot be 100% debunked. The thing is when there is absolutely no good reason to believe something existed or exists, why would you choose that over say, Rapokoten the magician-sorceror of the 1300s (hey, he could have existed)!